JPH0721469B2 - Method for analyzing composition of object to be measured by X-ray - Google Patents

Description

The present invention relates to a method for analyzing the composition of an object to be measured by a nondestructive measuring means utilizing X-rays.

"Prior art" When measuring the composition concentration and composition distribution of an opaque object non-destructively by irradiation with radiation, γ rays such as isotopes (Ga, Ir, Co) or X-rays are used as the radiation source. The radiation emitted from the irradiation system is applied to the object to be measured, and the intensity of the transmission line is measured and analyzed by the detection system.

By the way, in the case of a nondestructive measurement method using an isotope, it is said that industrialization is difficult due to reasons such as difficulty in obtaining the isotope, its strength being weak or too strong, and further having a short half-life.
The method using X-rays is widespread.

X-rays include white X-rays and monochromatic X-rays. For example, when the object to be measured is composed of two elements, white X-rays or monochromatic X-rays are usually used by scanning in which the X-ray irradiation system and the object to be measured are relatively moved. After irradiating the DUT with a line, the transmission line intensities for two or more specific wavelengths or energies are obtained by the detection system, and then the multi-layer division method based on the measurement data, the Abel conversion method, and other calculation methods are used. The composition distribution of the measurement object is determined.

At this time, it is said that the voltage of the X-ray source is 30 kv or more, and the intensity thereof is preferably the current conversion value of the X-ray source, which is 10 mA or more. If this current value is low, the X-ray dose becomes small and the measurement takes time.

The wavelength λ (angstrom) of the X-ray is about λ = 12.4 / V when the tube voltage kv applied to the X-ray source is V.

It is preferable to measure the intensity of the transmission line in about 1 minute, and it is said that the longer the time, the higher the measurement accuracy.

[Problems to be Solved by the Invention] Generally, when the radiation source is moved during X-ray scanning, the moving equipment becomes large in scale, and the radiation source becomes unstable.

In order to deal with this, when moving the object to be measured, it is conceivable to extract two or more kinds of monochromatic X-rays from the white X-rays by the diffracting means and irradiate them to the object to be measured. The measurement time becomes longer because the optical axes of the lines do not match.

In addition, even if an attempt is made to measure an object to be measured on a production line online, only the offline control can be adopted because the object to be measured for X-ray scanning cannot be moved. With such offline control, the composition of the object to be measured can be analyzed in real time. Can not do it.

In view of the above problems, the present invention is intended to provide a method capable of performing composition analysis of an object to be measured in a single time without moving the object to be measured, an X-ray source, or the like, and realizing online control. is there.

[Means for Solving Problems] In the method for measuring an object to be measured by X-rays according to the present invention, in order to achieve the intended purpose, white X-rays are radiated over the entire area between the measuring parts of the object to be measured. X-ray source, a plurality of collimators for branching a plurality of transmission lines (transmission white X-rays) that have passed through the object to be measured, and the transmission lines are diffracted to obtain a plurality of these transmission lines. A plurality of single crystals for extracting as characteristic X-rays, and a plurality of X-ray detectors for measuring a plurality of types of characteristic X-ray energies incident through the respective single crystals,
And that the X-ray detectors arranged on the side of the irradiation region of the white X-rays emitted from the X-ray source and adjacent to each other face the X-ray source, respectively, and that the DUT is an X-ray. The collimator is placed at a fixed position between the source and each X-ray detector, each collimator is placed between the object to be measured and each X-ray detector and adjacent to each other, and each single crystal is also , Which is arranged between the object to be measured and each X-ray detector and corresponds to these collimators and X-ray detectors in order to make the transmission line branched by each collimator enter each X-ray detector. And, when analyzing the composition of the object to be measured through the above means, irradiating white X-rays emitted from the X-ray source over the entire measurement portion of the object to be measured, Transmission line after passing through each collimator and each single crystal Branching and diffracting, making each characteristic X-ray extracted by these branching and diffraction incident on each X-ray detector, and measuring the energy intensity of each characteristic X-ray separately by each X-ray detector. It is characterized in that the composition of the measured object is analyzed.

[Operation] In the case of the method of the present invention, white X-rays are radiated over the entire area between the measurement parts of the object to be measured, so there is no need to move and scan the X-ray source, the object to be measured, and the object to be measured is transmitted. Subsequent transmission lines are branched and diffracted by a plurality of collimators and a single crystal, and the energy intensity of each characteristic X-ray after branching and diffraction is measured separately, so that the composition of each part between measurement parts can be known.

Therefore, it becomes possible to analyze the composition of the object to be measured in a short time because the above-mentioned scanning is not necessary and the composition of each part between the measuring parts can be determined. Even the DUT above can be analyzed online for composition.

[Examples] Examples of the method of the present invention will be described below with reference to the drawings.

In the embodiment of FIG. 1, 1 is an X-ray source, 2 is a manifold, 3a to 3f are collimators, 4a to 4f and 5a to 5f are single crystals, 6a to 6f are X-ray detectors, and 7 is a manifold 2 and a collimator. It is an opaque measured object arranged between 3a to 3f.

When carrying out the method of the present invention in FIG.
Is disposed between the manifold 2 and the collimators 3a to 3f, and the white X-rays as shown in FIG.
Multiple beams (diameter approx.
(About 1 mm), and these beams are irradiated over the entire width direction of the DUT 7.

The white X-rays thus radiated to the DUT 7 are transmitted through the DUT 7, and the transmitted X-rays (transmission lines) are collimated by the collimator 3a.
Pass each ~ 3f.

At this time, the collimators 3a to 3f block noise such as X-rays reflected from the DUT 7.

The transmission lines transmitted through the collimators 3a to 3f are single crystals 4a to 4f and 5a.
.About.5f are diffracted under Laue conditions and Bragg conditions to form characteristic X-rays as shown in FIG. 3, and these characteristic X-rays are incident on X-ray detectors 6a-6f.

The X-ray detectors 6a to 6f are, for example, semiconductor detectors, scintillation tubes, etc., and the characteristic X-rays are the X-ray detectors 6a.
.. to 6f, the X detectors 6a to 6f measure the energy of the characteristic X-ray according to the composition distribution concentration of the DUT 7.

Further, the X-ray detectors 6a to 6f input a signal corresponding to the intensity of the detected X-ray energy to an electronic computer (not shown), and the electronic computer electrically or electronically operates the input signal to measure the measured object. The composition of the product 7 is analyzed.

As the X-ray source 1 for emitting white X-rays, a high voltage with a voltage of about 200 kv and 350 kv is used.
Tungsten is used as the target in the wire tube.

As described above, the manifold 2 has a white X-ray diameter of about 1 m.
Although the beam is branched into about m beams, at this time, the optical axes of the beams and the collimators 3a to 3f are made to coincide with each other.

An example of the object to be measured is a porous preform for an optical fiber made of SiO ₂ and GeO _2, and the object to be measured 7 is Si or Ge.
When the number of beams is 20 or more, the analysis accuracy is improved.

When the DUT 7 is the two components as exemplified above,
Predetermined measurements are performed on the energies E1 and E2 diffracted by the single crystals 4a to 4f and 5a to 5f.

Besides, before the measurement of the DUT 7 is started, that is, before the DUT 7 is arranged between the manifold 2 and the collimators 3a to 3f, the X-ray intensity in the absence of the DUT 7 is measured. Then, the above-described measurement analysis is performed.

Another embodiment of the method of the present invention will be described below with reference to FIGS.

In this embodiment, after the white X-rays emitted from the X-ray source are narrowed down by the shield plate 8 made of Pb, this is irradiated to the object 7 to be measured, and then the transmitted rays are further narrowed down by the collimators 3g to 3s. It is incident on the detectors 6g to 6s.

At this time, as shown in Fig. 5, the single crystal is placed in the collimators 3g to 3s.
9g to 9s are arranged, and the energy satisfying the Laue condition and the Bragg condition such as the following formula is taken out.

nλ = 2d sin θ nhc / E = 2d sin θ n: integer, h: Planck's constant, c: speed of light, E: energy (kv), d: lattice spacing.

In the embodiment of FIGS. 4 and 5, only one energy is diffracted as shown in FIG. 7, but when analyzing the composition of the DUT 7 composed of two components as described above, it is necessary to analyze the composition according to these compositions. Single crystal 9g ~ 9s so that each energy E1 and E2 can be measured
Alternate the angle θ of.

FIG. 8 shows single crystals 4a to 4f in the embodiment shown in FIG.
5a to 5f are arranged on the rotary tables 10a to 10f so that the energies E1 and E2 corresponding to predetermined two components can be taken out so that the angle θ of these single crystals can be changed.

Next, more specific examples of the method of the present invention will be described.

When a porous preform for optical fiber having an outer diameter (diameter) of 80 mm and a length of 1000 mm was produced by the VAD method, the composition of the measurement object was analyzed online as the measurement object.

The measuring means at this time is generally as shown in FIG. 1, and a white X-ray source of 100 kv and a manifold of 30 X-ray beams were used.

After each X-ray beam passes through the object to be measured, it is made to coincide with the optical axis of the collimator, and a single crystal is arranged after the collimator as shown in FIG. 8, and the energy from the single crystal is incident on the detector. I was made to do it.

As the turntable for supporting the single crystal, a turntable whose rotation angle in seconds can be precisely controlled was used. The angle θ of each single crystal by the turntable was 100 kv for the white X-ray source, so E1 = It was adjusted so that the energy of 50kv and E2 = 80kv could be taken out.

The composition of the porous preform for optical fiber, which is the object to be measured, was analyzed under the above conditions.
It was possible to perform in 10 seconds, and by controlling the synthesis conditions of the porous base material based on the analysis result, a porous base material having a desired refractive index distribution was obtained.

"Effects of the Invention" As described above, when the method of the present invention is used, an X-ray source,
It is not necessary to scan the object to be measured, the composition of the object to be measured can be known in a short time, and even the object to be measured on the manufacturing line can be subjected to online composition analysis.

[Brief description of drawings]

FIG. 1 is an explanatory view schematically showing an embodiment of the method of the present invention, and FIG.
The figure is an energy characteristic diagram of white X-rays in the embodiment,
FIG. 3 is an energy characteristic diagram of characteristic X-rays in one embodiment thereof, and FIG. 4 is an explanatory diagram schematically showing another embodiment of the method of the present invention,
5 is a sectional view of a collimator in another embodiment, FIG. 6 is a white X-ray energy characteristic chart in another embodiment, FIG. 7 is a characteristic X-ray energy characteristic chart in another embodiment, and FIG. FIG. 4 is a schematic explanatory view showing an example in which the single crystal in the above one example is supported by a turntable. 1 ... X-ray source 2 ... Manifold 3a-3f ... Collimator 3g-3s ... Collimator 4a-4f ... Single crystal 5a-5f ... Single crystal 6a-6f ... X-ray detector 7 ... Measured Object 8 …… Shield plate 9g ～ 9s …… Single crystal 10a ～ 10f …… Turning table

Front page continuation (72) Inventor Fumihiko Abe No.6 Hachiman Kaigan Dori, Ichihara City, Chiba Furukawa Electric Co., Ltd. Chiba Electric Wire Works (56) References JP-A-56-22925 (JP, A) JP-B-43- 21920 (JP, B1) "X-ray diffraction technology" published by the University of Tokyo Press in 1979 Page 14 Figure 1.4

Claims (1)

[Claims] 1. A white X over the entire area between the measurement parts of the object to be measured.
X-ray source for irradiating X-rays, a plurality of collimators for branching a plurality of transmission lines (transmission white X-rays) after passing through an object to be measured, and diffracting each of the transmission lines to transmit these A plurality of single crystals for extracting the rays as a plurality of types of characteristic X-rays and a plurality of X-ray detectors for measuring a plurality of types of characteristic X-ray energies incident through the respective single crystals are provided. And that the X-ray detectors arranged on the irradiation area side of the white X-rays emitted from the X-ray source and adjacent to each other face the X-ray source, respectively, It is arranged at a fixed position between the X-ray source and each X-ray detector, each collimator is arranged between the object to be measured and each X-ray detector, and adjacent to each other. The crystal is also placed between the DUT and each X-ray detector, and each crystal The collimator and the X-ray detector correspond to the transmission lines branched by the laser beam to the respective X-ray detectors, and the composition of the object to be measured is analyzed through the above means. Sometimes, the white X-ray emitted from the X-ray source is applied to the entire area between the measurement parts of the DUT, and the transmission line after passing through the DUT is branched and diffracted by each collimator and each single crystal. The characteristic X-rays extracted by the branching and diffraction are made incident on the respective X-ray detectors, and the energy intensities of the respective characteristic X-rays are individually measured by the respective X-ray detectors to determine the composition of the object to be measured. A method for analyzing the composition of an object to be measured by X-ray, which comprises analyzing.